A draw-extended TTG (Tech Target Gun). How much draw does it have?
3.5". In contrast, a stock TTG has 1-7/8" (1.875"). That's an 87% increase in volume!!!
For the TL;DR crowd, here's the internals:
Basically, the rear PT flange is mounted where the front PT flange used to go. There, go forth and mod, ye TL;DRs!
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Materials:
- 1-5/8" of 1" PVC
- 1/2" CPVC coupler, cut in two OR 1/2" CPVC cap drilled out
- 1/2" PVC coupler OR 1/2" of 3/4" PVC
- E-tape
- 4-1/2" of [k26]
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Tools:
- Hacksaw
- Rubber mallet
- Pliers
- File
- (Optional, but recommended) calipers, or at least a ruler
- (Optional, but recommended) boltcutters
- (Optional, but recommended) scissors
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Unfortunately, this isn't an as-you-go writeup. I built it out of desperation, and found it to be amazingly effective, so I wanted to share the steps. However, I didn't take pictures as I went, so all I can do is describe what to do and show the end results.
First a bit of background - my amped-up TTGs don't have padded plunger heads, and do break the plunger tube (PT) face off the rest of the PT. Most of the time, that can be fixed with a bit of epoxy. In this case, the PT face shattered, so I had to devise something else.
This is the something else: a universal coupler as the PT face. A "universal coupler" is one that will take either 1/2" CPVC or 1/2" PVC. Pedants among you will point out it won't take mongo and above darts. Yeah, waddeah. STFU&FOAD, already.
Here's a "business end" shot to show what I mean:
In this case, I already had a universal coupler lying around, so it seemed like a good way to use it. You can substitute a chunk of 3/4" PVC, with the requisite elbow grease and percussive persuasion, in place of the 1/2" PVC coupler.
Even using a 1/2" PVC coupler, you will need to add some sweat and mallet-work. I reamed out the inner edge of the 1" PVC so it had a slight bevel, then sanded the end of the 1/2" PVC coupler containing the 1/2" CPVC coupler down so it somewhat fit, then applied momentum in the form of the rubber mallet.
As you can see, the front end of the 1" PVC is slightly flared from the force-feeding.
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Enough about the ©PVC-y bits. Let's talk PT.
Two take-aways in this pic. First is the e-tape. That's all that's holding the 1" PVC to the PT. There's a wrap or two more of e-tape than is sufficient to meet the coupler's ID, so a rubber mallet is required to join the two.
The second is the flattened flange. Because of the way the shell is designed, the groove for the PT front flange is shallower on the sides than the one for the PT rear flange, so some adjustments are needed. File down both sides of the PT rear flange, but leave the top and bottom in place.
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Now, the shell.
The rear is cut down to the rear bulkhead for the catch. The front is chopped down to the 1" PVC needs to protrude. For me 5-5/8" from the cut-down bulkhead is a workable length, but it may be better to just lay the modified PT on with the rear flange in the front groove and eyeball it.
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Lastly, the plunger.
As you can see, I'm using 4-1/2" of [k26]. Boltcutters are highly recommended for cutting down the spring. Please note this is too short for the spring to fully push the plunger head (PH) to the PT face. In other words, when unprimed, the spring will rattle and slide along the plunger rod (PR) a bit. However, this is the maximum length for the catch to work, and it only barely does.
The spring rest (black part on the left of the PR above) has been cut down, again to give the spring maximum compressed distance.
The catch spring is stock, though the bottom has been crimped with the pliers slightly to keep it from sproinging free when the blaster is opened. I've not had a problem with it prematurely firing - my catch difficulties are just with the catch sometimes failing to engage.
The PH end of the spring is likewise crimped. This is so it doesn't try to work it's way under the O-ring.
Finally, there's a wrap or two of e-tape under the O-ring.
The screw securing the PH to the PR has been replaced with something longer and wider. (All together now, "TWSS." Okay, done.)
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Miscellany:
- Ranges. Yeah, we haz'em.
Out of 10 test shots out of a 5" long CPVC barrel, I got results ranging from 69' to 114', with an average of 105'.
114'
108'
105' * 4
96'
87' * 2
78'
69'
Mind you, the TTG seems to fire high no matter what I do (short of aiming low, which isn't really realistic when using this on the field). I'd decrease ranges by 10% if we want to talk level flight, at least in theory.
- Build time. I'd say 2 hours, going slow.
- Bungees. As much as I love fuglifying my blasters with bungees, I wouldn't advise it. In a stock TTG, the rear chunk of the shell has a channel to keep the PR straight-ish. With this mod, that's gone, so the PR will apply any torque directly to the rear catch bulkhead. Couple that with the shape of the handle, and the bungee will ride up, guaranteeing torque.
- Complexity. I'd rank this fairly low. The hardest part would be getting the [k26]. I figure any modder who has access to K26s has already done the de riguer NF/Jolts, and this will be nothing new.
- Universal coupler. No, it's not a required part of this build. I had one lying around, and I needed to mount the half-CPVC coupler in something to nest it in the 1" PVC. My next instance of this will use the drilled out 1/2" CPVC cap and a chunk of 3/4" PVC.
OTOH, just for shits-n-grins, I tossed a 6-shot Spears-wye hopper on this, and it fired. I didn't have a chance to range-test it, but it launched a dart. Out of a TTG!
Questions/comments/flames?
Edited by taerKitty, 14 December 2011 - 12:24 PM.
